Motor driving apparatus, sheet conveyance apparatus, document feeding apparatus, document reading apparatus and image forming apparatus

A sheet conveyance apparatus comprising:

• a conveyance roller configured to convey a sheet;
• and
• a motor configured to drive the conveyance roller,
• a motor driving apparatus that includes
• a driving circuit that includes a plurality of switching elements constituting an H bridge circuit, and to which a winding of the motor,
• a detector configured to detect a driving current that flows through the winding of the motor,
• a pulse generator configured to generate a PWM signal that controls ON and OFF operations of the plurality of switching elements and includes a pulse at a first level and a pulse at a second level that is different from the first level, and
• a corrector configured to sample a current value of the driving current detected by the detector, and correct the current value,
• wherein, if a duty ratio that indicates a proportion of a first period in which the PWM signal is at the first level, to a period of the PWM signal, is greater than a predetermined value, the corrector samples a current value of the driving current detected by the detector, in the first period, and if the duty ratio is smaller than the predetermined value, the corrector samples a current value of the driving current detected by the detector, in a second period in which the PWM signal is at the second level,
• wherein the corrector corrects the current value sampled in the first period, based on a first correction value that reduces the current value, and corrects the current value sampled in the second period, based on a second correction value that increases the current value,
• wherein the pulse generator generates the PWM signal based on the current value corrected by the corrector,
• wherein the motor driving apparatus controls driving of the motor.

A document feeding apparatus comprising:

• a document stacking unit on which a document is stacked,
• a feed roller configured to feed a document stacked the document stacking unit;
• and
• a motor configured to drive the feed roller, a motor driving apparatus that includes
• a driving circuit that includes a plurality of switching elements constituting an H bridge circuit, and to which a winding of the motor is connected,
• a detector configured to detect a driving current that flows through the winding of the motor,
• a pulse generator configured to generate a PWM signal that controls ON and OFF operations of the plurality of switching elements and includes a pulse at a first level and a pulse at a second level that is different from the first level, and
• a corrector configured to sample a current value of the driving current detected by the detector, and correct the current value,
• wherein, if a duty ratio that indicates a proportion of a first period in which the PWM signal is at the first level, to a period of the PWM signal, is greater than a predetermined value, the corrector samples a current value of the driving current detected by the detector, in the first period, and if the duty ratio is smaller than the predetermined value, the corrector samples a current value of the driving current detected by the detector, in a second period in which the PWM signal is at the second level,
• wherein the corrector corrects the current value sampled in the first period, based on a first correction value that reduces the current value, and corrects the current value sampled in the second period, based on a second correction value that increases the current value,
• wherein the pulse generator generates the PWM signal based on the current value corrected by the corrector,
• wherein the motor driving apparatus controls driving of the motor.

A document reading apparatus comprising:

• a document stacking unit on which a document is stacked;
• a feed roller configured to feed a document stacked the document stacking unit;
• a motor configured to drive the feed roller;
• a reading unit configured to read the document that is fed by the feed roller;
• a motor driving apparatus that includes
• a driving circuit that includes a plurality of switching elements constituting an H bridge circuit, and to which a winding of the motor is connected,
• a detector configured to detect a driving current that flows through the winding of the motor,
• a pulse generator configured to generate a PWM signal that controls ON and OFF operations of the plurality of switching elements and includes a pulse at a first level and a pulse at a second level that is different from the first level, and
• a corrector configured to sample a current value of the driving current detected by the detector, and correct the current value,
• wherein, if a duty ratio that indicates a proportion of a first period in which the PWM signal is at the first level, to a period of the PWM signal, is greater than a predetermined value, the corrector samples a current value of the driving current detected by the detector, in the first period, and if the duty ratio is smaller than the predetermined value, the corrector samples a current value of the driving current detected by the detector, in a second period in which the PWM signal is at the second level,
• wherein the corrector corrects the current value sampled in the first period, based on a first correction value that reduces the current value, and corrects the current value sampled in the second period, based on a second correction value that increases the current value,
• wherein the pulse generator generates the PWM signal based on the current value corrected by the corrector,
• wherein the motor driving apparatus controls driving of the motor.

An image forming apparatus comprising:

• an image forming unit configured to form an image on a recording medium;
• a conveyance roller configured to convey the recording medium;
• a motor configured to drive the conveyance roller;
• a motor driving apparatus that includes
• a driving circuit that includes a plurality of switching elements constituting an H bridge circuit, and to which a winding of the motor is connected,
• a detector configured to detect a driving current that flows through the winding of the motor,
• a pulse generator configured to generate a PWM signal that controls ON and OFF operations of the plurality of switching elements and includes a pulse at a first level and a pulse at a second level that is different from the first level, and
• a corrector configured to sample a current value of the driving current detected by the detector, and correct the current value,
• wherein, if a duty ratio that indicates a proportion of a first period in which the PWM signal is at the first level, to a period of the PWM signal, is greater than a predetermined value, the corrector samples a current value of the driving current detected by the detector, in the first period, and if the duty ratio is smaller than the predetermined value, the corrector samples a current value of the driving current detected by the detector, in a second period in which the PWM signal is at the second level,
• wherein the corrector corrects the current value sampled in the first period, based on a first correction value that reduces the current value, and corrects the current value sampled in the second period, based on a second correction value that increases the current value,
• wherein the pulse generator generates the PWM signal based on the current value corrected by the corrector,
• wherein the motor driving apparatus controls driving of the motor,
• wherein the image forming unit forms an image on the recording medium that is conveyed by the conveyance roller.